The problem with the "Freemium" model is that they become pay to win, and thrive off inbalanced gameplay and grind-tastic leveling to force you to pay money because the gameplay experience is too frustrating and boring to play with the default tools. That is not how I want my games to play.
It would be like playing a chess game where you are told that for a pound each, you could replace your pawns with queens. Some people will not pay at all, some will buy one or two extra queens, and some people will go the whole hog and pimp their board with more queens than a gay pride festival, this creates completely unbalanced matches where your success depends on how much you paid for it, and the guy with the harem of death isn't going to be having any more fun than the vanilla chess guru because every match he plays he curbstomps with no difficulty whatsoever, no need of strategy, and no real threat.
When playing a multiplayer game balance is key. No one weapon or class or perk should be too powerful, or give an unfair advantage, or the game will homogenise into a one strategy rush-fest. Unfortunately free to play games need the unbalance and need unfair upgrades to function and force people to buy their way to success. I don't like being held in a vice like that.
We gamers are a fickle bunch, we like being able to claim what are ours, that's why things like on disk DLC, day one DLC, regular DLC, exclusive shop bonuses, DRM, etc. etc. etc. (basically anything that restricts our access and freedom to the content we've bought) is so hated and complained about. When you buy in a F2P game you don't own anything, the stuff you do buy can be sidelined and gimped, or eclipsed by better stuff released for sale the next day, and power creep will ensure that it will eventually be eclipsed by a more powerful, better version that you will have to shell out for again to stay on top.
There is no security for your purchases in F2P, and security of our bought products is a really important issue in the gaming community.